This invention relates to regenerative furnaces and their operation, and in particular to the type of regenerative furnace commonly employed in the manufacture of flat glass. The regenerators used in such furnaces are usually comprised of a gas-pervious bed of refractory material, such as a stacked arrangement of bricks, sometimes called "checker packing", through which hot exhaust gases are passed during one cycle in order to heat the packing. In alternate cycles, the flow is reversed and the heat stored in the packing serves to preheat combustion air passing through the regenerator. The regenerators are generally employed in pairs, with one on either side of the combustion chamber. While one regenerator is absorbing heat from the exhaust gas, the other is heating incoming air.
Because flat glass furnaces typically include a relatively large number of burner ports (usually about four to eight on each side) spaced several feet apart from one another, the length of a regenerator bed associated therewith usually has a length which is several times greater than its height or width. And because of construction expediencies, the main flue carrying gases to and from each regenerator is usually located at one end of the regenerator. This arrangement unfortunately sets up lateral flow in the upper plenum and therefore an uneven flow distribution in the regenerator packing during the exhaust cycle, which has been found to cause the portion of the packing near the flue to become hotter than other portions of the packing. This localized overheating may often be reinforced in the subsequent firing cycle, during which the flow of incoming air has been detected favoring the end of the packing away from the flue so that the flue end is cooled less than the remainder of the packing. As a result, the flue end portion of the packing tends to deteriorate faster than others, thereby shortening furnace life. Furthermore, because the stored heat is concentrated in one portion of the packing, the efficiency with which air is preheated in the firing cycle is reduced. It is an object of the present invention to overcome these disadvantages.
U.S. Pat. Nos. 1,836,412 and 2,813,708 relate to modifying the flow patterns in regenerators. Both employ rigid baffles designed primarily for the purpose of rendering the air flow through the checker packing more uniform during the firing cycle. It is not apparent, however, how such arrangements could sufficiently influence flow in the opposite direction through the packing during the exhaust cycle to avoid concentrating heat at the flue end of the packing. Moreover, such baffle arrangements could change the gas flow pattern in the space beneath the packing during the exhaust cycle, thereby promoting lateral flow of the exhaust gases along the plenum above the packing and then into the packing at the flue end.